1. Field of the Invention
The invention relates to a swivel chair consisting of an upper frame comprising a seat and, optionally, a back rest, consisting of an underframe and a supporting column proceeding between the upper frame and the underframe, the upper frame being pivotally mounted at the upper end of the supporting column by means of a bracket and the supporting column being mounted at the underframe.
2. Prior Art
Such swivel chairs are known for example from DE-PS 812 705, where a chair is shown, the seat of which is pivotally disposed on the underframe. This chair, although pivotal, is not stackable because the underframe does not fit over the seat and the back rest. A chair is known from DE-PS 728 006 in which case only its seat is pivotally mounted on the underframe, which cannot, however, be stacked. It is thus a disadvantage that, when not used or when stored, they require a relatively large individual storage space.
From FR-PS 13 83 394 a chair is known, consisting of a supporting frame, comprising a seat and a back rest. The supporting frame consists of a single, central tube, which is linked with an angularly spaced foot part. The underframe supporting the seat is in this context bent inwardly from the vertical projection so that the upper part of this chair can be springy. This chair is, however, not pivotal and can also not be stacked due to its single tube construction. Finally, a chair is known from U.S. Pat. No. 37 74 960 in which case a springy underframe supports a seat and a back rest, linked to the seat. The seat and the back rest are in this context longitudinally spaced. Such a chair, although stackable, is, however, not pivotal so that after a certain period of use fatigue and loss of concentration of the person using it, occurs.
It is the object of this invention to so design a swivel chair of the type described in the opening paragraph which is stackable.